There are a contact type charging method and a noncontact type charging method in methods of charging a secondary battery mounted in an electronic device such as a portable terminal, a video camera, and the like. The contact type charging method performs charging by allowing an electrode of a power receiving apparatus and an electrode of a power feeding apparatus to come into contact with each other.
Due to a simple device-structure thereof, the contact type charging method is generally used in various application fields. However, there is present a difficulty in connecting connectors according to charging a battery that is a power source using a wired charger.
To solve this, the noncontact type charging method using electromagnetic induction by installing corresponding coils at both sides of a power receiving apparatus and a power feeding apparatus has been provided.
A noncontact type charger is reduced in size by winding coils around a ferrite core as a magnetic core.
In this case, the power feeding apparatus is formed using a method of arranging a plurality of planar coils to allow a part to be overlapped with one another and then fixing the coils to a shielding sheet using adhesives.
That is, a plurality of planar coils 2 and 3 are connected to stack a part of a planar coil 2 above a planar coil 3 to allow a part to be mutually overlapped. In the case of the plurality of planar coils 2 and 3 connected while partially overlapped as described above, the planar coil partially stacked thereabove does not come into direct contact with a shielding sheet 4 due to a thickness of the planar coils.
To solve this, a method of allowing other parts except an overlapped part to come into contact with a shielding sheet by forming a step structure by mechanically twisting a part of the planar coil stacked thereabove.
However, during a process of mechanically twisting or bending the planar coil, the planar coil is damaged and a defective occurs.
Additionally, since an additional operation of mechanically twisting the planar coil partially stacked thereabove to allow the planar coil to come into contact with the shielding sheet is necessary, a manufacturing process is complicated and inconvenient and production yield is reduced.